First records of aneuretine ants (Hymenoptera: Formicidae: Aneuretinae) in late Eocene Rovno amber (Ukraine)

Aneuretinae is an enigmatic ant subfamily with poorly defined morphological boundaries. Aneuretus simoni Emery, 1893, found only in Sri Lanka, is a “living fossil”, the only known extant species of Aneuretinae. In the distant past, however, Aneuretinae was more diverse and widespread, including eight extinct genera spread across North America, Europe, and the Russian Far East. Here, we report two fossil Aneuretinae species, Protaneuretus succineus Wheeler, 1915 and Paraneuretus tornquisti Wheeler, 1915, found in late Eocene (Priabonian, 37.8–33.9 Ma) Rovno amber (Ukraine), providing distinguishing morphological features and measurements. These species, the first recorded Aneuretinae in Rovno amber, were originally described from Baltic amber of similar Priabonian age. These new records raise the number of reported ants in Rovno amber to 77 species from 39 genera and 9 subfamilies, and indicate that in the late Eocene Aneuretinae were distributed both on the northern and southern coasts of the Paratethys. Fossil evidence suggests that Aneuretinae originated in the Northern Hemisphere and only entered India and Sri Lanka after the Indian subcontinent collided with Asia ~59 Ma. Why Aneuretinae survived to the present only in Sri Lanka remains a mystery.